A clutch assembly for a transmission is configured to selectively interconnect a first rotatable member with a second rotatable member by engagement of a clutch pack. The clutch assembly includes a piston dam and a piston which is axially moveable with respect to the piston dam and configured to selectively abut and engage the clutch pack to interconnect the first and second rotatable members.
A clutch housing encloses the piston, piston dam and clutch pack. A piston apply cavity is formed between the housing and piston to receive fluid from a clutch apply feed orifice to actuate the piston. A piston compensator cavity is formed between the piston dam and piston to receive fluid from a piston compensator feed orifice.
In order to achieve smooth, consistent shift feel quality when changing gears, a force balance between the piston apply cavity fluid and the piston compensator cavity fluid must be maintained. In conventional clutch assemblies, the piston compensator cavity fluid volume varies during clutch operation and must be frequently adjusted to maintain the force balance between the cavities and, in turn, smooth clutch operation.
Thus, there is a need for a method of comprehending the fluid volume variations that occur in the piston compensator cavity so that better fluid fill command pressures can be made when compensating for the fluid volume variations.